Improvement of sensitivity in neutron activation analysis by selective absorption of high-intensity low-energy gamma-rays

A counting technique involving selective attenuation of matrix activity by a lead absorber is described. This technique applies to all cases in which it is necessary to detect low-intensity high-energy γ rays in the presence of high-intensity low-energy γ-rays emitted by the matrix. An improvement in sensitivity of several orders of magnitude can be achieved in some cases. The technique was verified for three matrices and the attenuation factors for a 1 cm lead absorber were calculated for all radioisotopes. Criteria for the choice of the most suitable absorber are discussed.